1. Field of the Invention
The present invention relates to a safety shield for hollow and solid medical needles, of the type which are used for entry into the body, into closed intravenous and intraarterial catheter systems for access, sampling, injection of medications, and transferring specimens to closed containers, and are withdrawn after use, the safety shield performing a self-recapping function for the sharp tip of the needle.
2. Description of the Prior Art
Devices of known construction which utilize hollow medical needles include syringes with built-in needles, syringes with removable needles, vacuum-tube phlebotomy sets with removable needles, devices for catheter-over-needle cannulation of veins or arteries, devices for needle-over-catheter cannulation of veins or arteries, and trocar (solid needle)-and-catheter devices. Such devices are used for entering body cavities or spaces, the circulatory system, closed intravenous and intraarterial catheter systems, or specimen containers. All of these devices have in common the features of having a sharp end which can easily penetrate human skin, and having the ability to retain pathogens when withdrawn from a human body or closed catheter system which communicates with a human body, thus endangering the user of the device, in that accidential injury and self-contamination by the sharp point after use are possible.
Such known devices are supplied to the user with some form of cap that covers the sharp point prior to use. The protective caps known in the art provide little provision for safely replacing the cap on the needle point. After the needle and associated devices known in the art have been used, the needle and device must be placed in a puncture resistant container to be discarded. Injury and self-contamination due to accidential needle sticks may occur, either in the process of attempting to replace the protective cap, or by the lack of such protection on the sharp point in transit to the disposal container [Jagger J., Hunt E.H., Brand-Elnaggar J., Pearson R.D. Rates of needle-stick injury caused by various devices in a university hospital. New Engl J. Med 1988; 319:284-8.].
Accidential needlestick injuries continue to represent a significant percentage of the injuries which occur in the medical field. Appreciation of the extent of the needlestick injury problem was evident when on Aug. 21, 1987, the CDC recommended universal precautions to prevent transmission of HIV in the health-care setting, intended to apply to the care of all patients, not just those known to be infected with HIV or other blood-borne pathogens. [Recommendations or prevention of HIV transmission in health-care settings. MMWR 1987; 36:3S-18S.].
Recommendations pertaining to needlestick injury rely on refraining from recapping, purposely bending or breaking needles by hand, or removing needles from disposable syringes. An example of a specific recommendation is that, after they are used, disposable needles should be placed in puncture-resistant containers (such as product code SN6132, Becton Dickenson & Company, Rutherford, N.J. 07070) located as closed as practicable to the use area. This specific recommendation has been in place since 1982 [Acquired immunodeficiency syndrome (AIDS) precautions for clinical and laboratory staffs. MMWR 1982;31:577-80.].
While currently an unsafe practice, recapping a needle promptly once it is removed from the skin is laudable in intent. A needle on a syringe presents a hazard from the time it leaves the patient's skin until it is placed in a plastic container. During that time it must traverse an unpredictable environment filled with medical personnel, who may be reacting rapidly to extreme emergency, or inattentively to a routine task. Authors reporting a recent study of 326 needlestick injuries have indicated that, as a result of the study, it has yet to be determined whether recapping poses a greater risk than not recapping when a competing hazard is present. [Jagger J., Hunt E.H., Brand-Elnaggar J., Person R.D.; Rates of needle-stick injury caused by various devices in a university hospital. New Engl J Med 1988; 319:284-8.]. Laboratory phlebotomists currently lessen this problem by carrying a small needle container on their phlebotomy tray like that disclosed in U.S. Pat. No. 4,375,859, and marketed under product code 8900 by Sage Products, Cary, Ill. 60013, which allows relatively prompt removal of the used unrecapped needle from the hub of a vacuum-tube phlebotomy set, without proximity between needle point and fingers. This device still requires some unprotected needle transit, is not applicable for use with a variety of needles and related devices used by nursing personnel and physicians.
The Cooperative Needlestick Surveillance Group of the CDC found that of 938 health care workers exposed to potentially infective body fluid, 637 (68%) involved needlestick, and only 280 (44%) of these were preventable by observing recommended precautions [McCray E.; The Cooperative Needlestick Surveillance Group--Occupational risk of the acquired immunodeficiency syndrome among health care workers. N Engl J Med 1986; 314:1127-32.]. These figures suggest that the CDC recommendations would not have been sufficient to avoid 56% of injuries. A 1985 study from a medical center with a large AIDS population found that 15% of 239 housestaff and 10% of 39 laboratory staff had at least one needlestick exposure (voluntary enrollment in that study was 54% and 22% for housestaff and laboratory staff, respectively) [Weiss SH, Saxinger WC, Rechtman D, et al HTLV-III infection among health care workers. JAMA; 254:2089-93.]. This suggests not only an alarming rate of accidential exposure, but a need for improved protection against accidental needlesticks not heretofore believed available.
The CDC guidelines can not minimize the risk of needlestick injury occurring if the phlebotomist enters his/her own skin immediately after removing the needle or after the patient suddenly jerks his/her arm resulting in needle withdrawal. Similar risk occurs when withdrawing a needle from a resistant substance such as the rubber stopper of a vacuum tube, wherein the needle may disengage suddenly from the stopper, and in a reflexive rebound motion, may return to injure the hand holding the vacuum tube [Jagger J, Hunt EH, Brand-Elnaggar J, Pearson RD. Rates of needle-stick injury caused by various devices in a university hospital. New Engl J Med 1988; 319:284-8.]. While an institution can stress the CDC guidelines to its staff, it can not prevent human error or accident.
Several recent U.S. patents have been issued for devices which claim to render more safe the act of recapping a needle. Examples of such devices are found in U.S. Pat. Nos. 4,747,835; 4,659,330; 4,735,617; 4,726,446; 4,629,453; 4,743,233; and 4,747,837. These all require an intentional act on the part of the user to recap the needle, and are therefore not "self-recapping" in any manner of use. Such devices can not generally prevent rebound or similar injuries which occur rapidly after tip withdrawal. U.S. Pat. Nos. 4,747,835; 4,659,330; 4,743,233; and 4,747,837 relate specifically to the hypodermic syringe, require modification thereof, and are thus not applicable to other medical devices other than hypodermic syringes utilizing needles or to unmodified hypodermic syringes. U.S. Pat. Nos. 4,747,835; 4,659,330; 4,726,446; and 4,629,453 require the user to direct the needle point into a cap held in the opposite hand, claiming protection by means of a flange or a handle. While protection may be improved over previously known caps, the devices still require the second hand to be brought into close proximity of the needle point, and therefore the safety of this approach remains questionable.
There exists, therefore, a need in the art for a device which will immediately cap the needle with a penetration-resistant cover as soon as it is withdrawn from the skin to effectively prevent needlestick injuries. Such a device, if effective and sufficiently inexpensive, would likely be used to the exclusion of older venipuncture and needle equipment. Physical, psychological, and financial morbidity following needlestick accidents could be thereby avoided.
It is an object of the present invention to provide such a recapping device which immediately shields a medical needle after withdrawal of the contaminated sharp tip from a patient or other object, thereby significantly reducing the probability of needlestick injuries during disposal or further handling thereof.
It is a further object of the present invention to provide such a recapping device which may effectively close off an aperture in the recapping device through which the medical needle had previously protruded.